2016 Kumamoto earthquake sequence and its impact on earthquake science and hazard assessment

The Kumamoto earthquake sequence that started on 15th April, 2016 resulted in more than 60 fatalities and brought about serious damage to society. It is the first time that the seismic intensity of 7 (on the Japan Meteorological Agency scale) was recorded twice within two days, which unnerved the population in the affected areas and made the response difficult. The earthquakes occurred on known active faults where long-term probability was disseminated, but such complex activity was unexpected. This unique sequence will clearly have a significant impact on the field of earthquake science and related hazard assessment.

This special issue presents results obtained immediately after the event, focusing on multidisciplinary researches regarding the 2016 Kumamoto earthquake sequence, the relevant tectonics and associated phenomena.

We present the results of relocating 17,544 hypocenters determined from data recorded during the 2016 Kumamoto Earthquake sequence, during the interval between April 14, 2016, and August 31, 2016. For this, w...

In this study, we estimated source process of the 2016 Kumamoto earthquake from strong-motion data by using the multiple-time window linear kinematic waveform inversion method to discuss generation of strong m...

Large earthquakes occurred in the central part of Kumamoto Prefecture on April 14–16, 2016, causing severe damage to the northern segment of the Hinagu faults and the eastern segment of the Futagawa faults. Ea...

To evaluate local site effects in Kumamoto City, we installed six temporary seismic stations along a 6-km north–south survey line in the city immediately after the 2016 Kumamoto earthquake foreshock (Mj 6.4),...

This study investigates the missing data problem in the Japan Meteorological Agency catalog of the Kumamoto aftershock sequence, which occurred since April 15, 2016, in Japan. Based on the assumption that ear...

The pseudo point-source model approximates the rupture process on faults with multiple point sources for simulating strong ground motions. A simulation with this point-source model is conducted by combining a ...

In this study, the rupture process of the main shock of the Kumamoto earthquake, particularly the generation of strong ground motions in the frequency range relevant to structural damage, was investigated bas...

The nationwide strong-motion seismograph network of K-NET and KiK-net in Japan successfully recorded the strong ground motions of the 2016 Kumamoto earthquake sequence, which show the several notable character...

The 2016 Kumamoto earthquakes in Kyushu, Japan, started with a magnitude (M) 6.5 quake on April 14 on the Hinagu fault zone (FZ), followed by active seismicity including an M6.4 quake. Eventually, an M7.3 quake o...

The 2016 Kumamoto earthquake (Mw 7.0) occurred in the central part of Kyushu Island, southwestern Japan, on April 16, 2016. The mainshock triggered an event of maximum acceleration 700 gal that caused severe dama...

To understand the cause of heavy structural damage during the mainshock (on April 16, 2016) of the 2016 Kumamoto earthquake sequence, we carried out a field survey from April 29 through May 1, 2016, in Mashiki...

A two-stage scaling relationship of the source parameters for crustal earthquakes in Japan has previously been constructed, in which source parameters obtained from the results of waveform inversion of strong ...

We resolve the density structure of a possible magma reservoir beneath Aso, an active volcano on Kyushu Island, Japan, by inverting gravity data. In the context of the resolved structure, we discuss the relati...

Seismic activity is associated with crustal stress relaxation, creating inelastic strain in a medium due to faulting. Inelastic strain affects the stress field around a weak body and causes stress concentratio...

High-amplitude seismic waves from the Mw 7.0 Kumamoto earthquake of April 16, 2016, triggered another large earthquake 80 km to the NE roughly 30 s later. The source was located at shallow depths beneath the Y...

At the 2016 Kumamoto earthquake, surface ruptures were observed not only along the Futagawa fault, where main ruptures occurred, but also along the Hinagu fault. To estimate the slip distribution on these faul...

The 2016 Kumamoto earthquake (Kumamoto earthquake sequence) is an extremely high-seismicity event that has been occurring across Kumamoto and Oita Prefectures in Japan since April 14, 2016 (JST). The earthquak...

We have conducted observation of earthquake ground motion due to aftershocks of the 2016 Kumamoto earthquake at 26 temporary stations in damaged areas of Kumamoto city, Mashiki town, Nishihara village and Mina...

An Mw7.1 Kumamoto earthquake occurred at 01:25:05 on April 16, 2016 (JST). The earthquake involved a rupture at a shallow depth along a strike-slip fault with surface breaks. Near-fault ground motion records, ...

We estimate high-frequency (4–20 Hz) energy release due to the 2016 Kumamoto, Japan, earthquake sequence, within a time period from April 14 to 26 through envelope inversion analysis applied to the Hi-net cont...

An MJMA6.5 earthquake (foreshock) and MJMA7.3 earthquake (mainshock) struck Kumamoto Prefecture on April 14, 2016, and April 16, 2016. To evaluate the effect of crustal deformation due to the earthquake on the As...

We report precursory seismic patterns prior to the 2016 Kumamoto earthquakes, as measured by four different methods based on changes in seismicity that can be used for earthquake forecasting: the b-value method, ...

An ENE-trending ~30-km-long surface rupture emerged during the Mw = 7.0 16 April 2016 Kumamoto earthquake along the previously mapped Futagawa and northern Hinagu faults. This included a previously unknown 5-k...

On April 15, 2016, Kumamoto, Japan, was struck by a large earthquake sequence, leading to severe casualty and building damage. The stochastic finite-fault method based on a dynamic corner frequency has been ap...

During the passage of the seismic waves from the M7.3 Kumamoto, Kyushu, earthquake on April 16, 2016, a M5.7 [semiofficial value estimated by the Japan Meteorological Agency (JMA)] event occurred in the central p...

The 2016 Kumamoto earthquakes, including an Mw-7 right-lateral earthquake on April 15 (UTC), occurred along faults within the Beppu−Shimabara graben in central Kyushu, Japan. Previous studies showed that the g...

The 2016 Kumamoto earthquake sequence was a rare event worldwide in that the surface ruptures associated with the largest foreshock (Mj 6.5) of 21:26 (JST), 14 April ruptured again during the mainshock (Mj 7.3...

We analyze Bouguer anomalies in/around the focal region of the 2016 Kumamoto earthquake to examine features, such as continuity, segmentation and faulting type, of the active fault zones related to the earthqu...

The MJMA7.3 Kumamoto earthquake occurred on April 16, 2016, in the western part of Kyushu, at a depth of 12 km, on an active strike-slip fault. Here, we report on a relatively widespread activation of small remot...

We constructed and analyzed the ground surface displacement associated with the 2016 Kumamoto earthquake sequence using satellite radar interferometry images of the Advanced Land Observing Satellite 2. The ra...

We estimated the dip distribution of Oita–Kumamoto Tectonic Line located in central Kyushu, Japan, by using the dip of the maximum eigenvector of the gravity gradient tensor. A series of earthquakes in Kumamo...

The 2016 Kumamoto earthquake sequence started with an MJMA 6.5 foreshock occurring along the northern part of the Hinagu fault, central Kyushu, Japan, and the MJMA 7.3 mainshock occurred just 28 h after the fores...

We constructed the rupture process model for the 2016 Kumamoto, Japan, earthquake from broadband teleseismic body waveforms (P-waves) by using a novel waveform inversion method that takes into account the unce...